Hi Alexander, Hi Neil, On 2022-01-15 11:52, Stefan Agner wrote: > Hi Alexander, > > On 2022-01-15 11:02, Alexander Stein wrote: >> Hi Stefan, >> >> Am Donnerstag, 13. Januar 2022, 15:36:38 CET schrieb Stefan Agner: >>> Hi Neil, >>> >>> I am trying to use HDMI CEC on ODROID-N2+ using Linux 5.10.91. However, >>> I was unsuccessful: As far as I can tell cec-client uses the right >>> device (I disabled CONFIG_DRM_DW_HDMI_CEC since my kernel is still >>> missing your patch "drm/meson: dw-hdmi: disable DW-HDMI CEC >>> sub-driver"). But communication won't work, and dmesg prints timeout >>> messages: >>> >>> [ 68.831253] cec-meson_g12a_ao_cec: message ff 84 20 00 06 timed out >>> [ 71.134987] cec-meson_g12a_ao_cec: message ff 87 00 15 82 timed out >>> [ 73.438826] cec-meson_g12a_ao_cec: message f0 timed out >>> [ 75.742677] cec-meson_g12a_ao_cec: message f0 timed out >>> [ 78.046555] cec-meson_g12a_ao_cec: message f0 timed out >>> [ 80.350446] cec-meson_g12a_ao_cec: message f0 timed out >>> [ 82.654358] cec-meson_g12a_ao_cec: message 11 timed out >>> [ 84.958285] cec-meson_g12a_ao_cec: message 11 timed out >>> [ 87.262194] cec-meson_g12a_ao_cec: message 11 timed out >>> [ 89.566130] cec-meson_g12a_ao_cec: message 11 timed out >>> >>> I did a quick test with CoreELEC which uses the 4.9 downstream kernel, >>> CEC seems to work there. So it does not seem to be my hardware setup. >>> >>> A quick test with the latest Linux 5.16 shows the same errors. >>> >>> Do you happen to have an idea? Do you know if HDMI CEC using upstream >>> kernels worked at one point on that particular platform? >> >> I'm using Arch Linux on my ODROID-n2 (non-plus) and HDMI CEC works as >> expected. >> Currently I'm running a 5.15.13-1-aarch64-ARCH kernel. AFAICS the mentioned >> patch is mainline since v5.14. I can see my TV without issues. I have to add >> that not every cable is suitable for HDMI CEC, I have one where CEC does not >> work (in general). > > Hm, interesting, thanks for the datapoint! > > I tried to reproduce your findings, unfortunately I am not successful in > booting mainline using Arch Linux ARM so far. It seems it comes with > downstream 4.9 kernel by default (where CEC seems to work in this case > too). I then installed linux-aarch64 and adjusted the device tree, but > it seems that the downstream U-Boot 2015.01-10 has some hardcoded > "rsvmem" command which fails. How are you booting v5.14? FWIW, adjusted U-Boot load addresses fixed that issue: # Set load addresses setenv dtb_loadaddr "0x20000000" setenv loadaddr "0x1080000" setenv initrd_loadaddr "0x4080000" And I can confirm, HDMI CEC works with Arch Linux 5.15.13 kernel! > > It is a bit surprising that 5.15.13 works for you but 5.16 didn't for > me. That makes me wonder, could it be bootloader dependent? Are you > using downstream U-Boot? That assumption turned out to be wrong: I used our mainline based U-Boot 2021.10 instead of the Arch Linux ARM U-Boot, and HDMI CEC continued to work. I then moved to 5.15.13 as well to rule out any kernel changes. But still, in our configuration HDMI CEC did not work. I ended up diffing configuration, and noticed that we are using built-in CONFIG_CEC_CORE whereas Arch Linux uses it as a module. To build CONFIG_CEC_CORE as a module I had to change some other configuration from built-in to module, namely: - CONFIG_CEC_CORE=m - CONFIG_DRM_DW_HDMI=m - CONFIG_DRM_MESON=m - CONFIG_DRM_MESON_DW_HDMI=m With that change, HDMI CEC started to work in my builds too! With that change, it also works on Linux 5.10. I guess there is some ordering issue or something which makes it fail when those drivers are built-in? Note that I did not change CONFIG_CEC_MESON_G12A_AO, that driver was already a module before. -- Stefan
